Now, don’t freak out! But consider: People exist. Things in the universe exist. The planets in their courses exist. While there are clear limits to our knowledge, everyone knows what it means to exist.
God does not exist like we do.
If God does exist, then They is not God. All existing things are relative to one another in various degrees. It is actually impossible to imagine a universe in which there is, say, only one hydrogen atom. That unique thing has to have someone else imagining it. Existence requires existing among other existents, a fundamental dependency. If God also exists, then God would be just another fact of the universe, relative to other existents and included in that fundamental dependency of relation.
In other words, God could not be God. They would be at best some sort of super-alien, flitting about the creation flashing super powers, seemingly irrationally. That is what the Flying Spaghetti Monster is. Its “worshippers”, the “Pastafarians”, are the latest in a long line of skeptics, though with perhaps a finer sense of humor. And even if said Monster existed, it could not be God. There would be no reason to worship it; in fact, one would do well to avoid it and its “noodly appendages.”